Method and apparatus for draining liquid from containers



June 6, 1967 5 3,323,544

METHOD AND APPARATUS FOR DRAINING LIQUID FROM CONTAINERS Filed March 24, 1965 3 Sheets-Sheet 1 INVENTOR GUS FRANCIS ATTORNEYS G. FRANCIS 3,323,544

METHOD AND APPARATUS FOR DRAINING LIQUID FROM CONTAINERS June 6, 1967 3 Sheets-Sheet 2 Filed March 24, 1965 INVENTOR.

GUS FRANCIS a) ATTORNEYS June 6, 1967 e. FRANCIS 3,323,544

METHOD AND APPARATUS FOR DRAINING LIQUID FROM CONTAINERS Filed March 24, 1965 3 Sheets-Sheet .3 7

/POWER SUPPLY INVENTOR,

GUS FRANCIS y/Mazda) ATTORNEYS 3,323,544 METHOD AND AY'PARATUS FQR DRAINING LIQUID FRQM CUNTAINERS Gus Francis, 1430 S. Josephine, Denver, Colo. 8021i) Filed Mar. 24, 1965, Ser. l -lo 442,279 13 Claims. (Cl. 137-587) ABSTRAGT OF THE DISCLOSURE This invention relates to a method and apparatus for draining liquids from containers, more particularly, it relates to a method and apparatus for sequentially cutting a liquid outlet hole and an inlet hole in a container by means of explosively actuated cutters.

The invention is specifically directed to apparatus for draining liquids from a tank or container carried underneath an aircraft wing; however, it is by no means limited to this application as it can be used for cutting holes in various type containers, flat Work, and other material.

Various occasions arise where it is necessary to discharge liquids from tanks carried beneath the wings of aircraft. For example, in the use of aircraft in fighting fires or in crop dusting it may be desirable to release liquid fire retardant material or insecticides from tanks carried under the wings of the aircraft. Certain military applications now require the release of liquids from tanks carried beneath the wings of military aircraft.

The rapid and effective discharge of liquids from a suspended tank requires that an air hole he cut in the tank as Well as a liquid outlet hole in order to provide for effective flow of fluid from the outlet hole. It is well known that in order for liquid to flow rapidly from the outlet of a container without breathing an air inlet hole must be provided so that air can fill the space occupied by the liquid being discharged from the container. Accordingly, any method and apparatus providing for the effective release or discharge of liquids from a suspended tank must provide for the cutting of both an air inlet hole and a liquid outlet hole in the tank or container.

If the tank from which the liquid is to be discharged is carried on an aircraft, the air inlet hole on the top of the container must be out after the liquid outlet hole is cut in the bottom of the container. The reason for this is that if the air inlet hole on top is cut first and poisonous or corrosive liquids are being carried in the tank, these liquids will be discharged over the wings and other parts of the aircraft with resultant damage thereto, and the pilot and other personnel in the aircraft may suffer serious injury. Accordingly, it is necessary that the holes be cut sequentially, that is, that the liquid outlet hole in the bottom of the tank be cut before the air inlet hole in the top of the tank is cut so that all of the liquid being discharged from the tank will pass out of the liquid outlet hole in the bottom of the tank.

The apparatus for cutting the holes in the tank must be one Which provides instantaneous and reliable cutting of the holes upon actuation of the cutting mechanism by the pilot. It has been found that the most effective means for cutting the holes is the use of an explosive cutting States Patent Patented June 6, 1%

mechanism. Such mechanisms generate large forces. It is important that the cutter back up mechanism which is positioned on the outside of the tank not be shattered by the force of the explosion which effects cutting of the holes as shattering with consequent production of numerous fragments of metal, plastic and other material will result in serious damage to the aircraft.

Accordingly, it is an object of this invention to provide a method and apparatus for discharging liquids from containers.

It is another object of this invention to provide an apparatus for cutting holes in metallic and other rigid material.

It is another object of this invention to provide apparatus for sequentially cutting holes in containers and other objects.

It is a further object of this invention to provide explosively actuated cutters for cutting holes in containers and other objects which are not subject to fragmentation and shattering by the explosive which performs the cutting operation.

The invention in its broadest sense as applied to cutting holes in a container comprises two explosively actuated cutters adapted to be placed one on the bottom of the tank for cutting the liquid outlet hole and one on the top of the tank for cutting the air inlet hole, in combination with switching means which operates to actuate the cutter for the air inlet hole only after the liquid outlet hole has been cut. The sequential switching means is actuated by movement of the section of the tank cut out to form the liquid outlet hole. The explosive cutter itself forms an essential part of the invention and comprises a heavy metal annulus having an arch shaped, annular groove in its bottom edge facing outwardly with an annular concave explosive charge positioned in and conforming to the groove with its concave surface facing outwardly and having a metal lining on its concave surface, and a detona tion train for detonating the explosive charge.

In the preferred modification, a buffer layer of nonexplosive material is positioned between the explosive charge and the bottom of the groove in the annulus, the surface of the explosive is in the form of a V and two detonators degrees apart are used for redundancy in detonating the explosive cutting charge.

The invention will now be described in conjunction with the accompanying drawings where like parts are represented by like numerals and in which,

FIG. 1 is a schematic showing of a liquid tank or container provided with explosive cutters on its top and bottom;

FIG. 2 is a top plan view of the explosive cutter used on the top of the tank for cutting an air inlet hole;

FIG. 3 is a vertical cross section of the back-up annulus of the explosive cutter taken on the line 33 of FIG. 2;

FIG. 4 is a section taken on the line 4-4 of FIG. 2 looking in the direction of the arrows;

FIG. 5 is a top plan view of the explosive cutter used on the bottom of the tank for cutting the liquid outlet hole;

FIG. 6 is a section taken on the line 6-6 of FIG. 5 looking in the direction of the arrows;

FIG. 7 is a section taken on the line 77 of FIG. 5;

FIG. 8 is a cross sectional view of a modification of the explosive cutter of FIGS. 5 and 6 mounted on the bottom of a tank;

FIG. 9 is a bottom view of the modification of FIG. 8;

FIG. 10 is a simplified schematic diagram of the circuitry for actuating the detonation trains of the explosive cutters, and

FIG. 11 is a cross sectional view of the liquid outlet cutter annulus showing a modification of the means for draw them'inside the tank. I Y Y I 1 Referring to FIG. 2, the upper cutter 16 for cutting the I air'inlet hole is constructed in the form of an annulus'32 provided with'holes 33'and mating screws or bolts 34 forv attachment to tank 10. A conduit 36 and plug 37 are pro- 7 vided for electrical lead wires leading to the detonation ctuating the circuit for the air inlet cutter by outward I movement of the cut out plate for the liquid outlet.

Referringnow to FIG. 1, there is shown a tank 10 for suspension from the underneath side of the Wing of an aircraft by suspension lugs 12. The tank is for'carrying liquids to be discharged while the aircraft is in flight. The liquids, of course, may be poisonous corrosive or 14 and 16, respectively, are schematically shown mounted for cutting liquid outlet and air inletholes, respectively. A nozzle device 18 is connected by means of a flexible elbow 19to a mounting adapter 21 which is attached over 'a portion of the tank which'is to: be cut out to form the liquid outlet hole. The purpose of the nozzle, of course,

. is to control the stream of liquid leaving the tank.

Onemodification of the invention will'now be de scribed. Anchoring members 2t) and 22 are secured to the internal walls of the tank opposite the area of the open- I out portions move outwardly rather than inwardly after" being cut out and the springs 24 and 26 are necessary to train'of the cutter 16 as will be more fully explained later. The annulus 32 must be made of heavy metal, such as high strength steel in order to provide a sufiiciently heavy backup fo rthe explosive cutting charge tov prevent shattering'when the explosive charge is detonated. I

Referring to FIGS. 3 and 4 it will. be seen that the annulus 32 is of solid cross section and is constructed with an annular groove 40 facing outwardly toward the bottom of the annulus. The groove 40 extends entirely around the annulus in this modification. The groove is arch shaped and has no square corners. This shape provides the greatest strength for the surrounding metal and presents no points of weakness to promote shattering, such as corners which would result from a groove of rectangular shape. An annular layer 41 of resin such as epoxy resin, referred to hereinafter as a buffer element or layer, is potted into the bottom of the groove 40. The buffer layer 41 may be of suitable non-metallic material, such as nylon, Teflon or other suitable plastic. The upper surface of the buffer layer 41 is V-shaped and V-shaped explosive cutting charge 42 inside metal casing 43 is seated in the V of buffer layer 41. The explosive cutting charge 42 is in the shape of an annulus and is positioned in the groove with its concave surface facing outwardly.

The explosive cutting charge in the preferred modification is V shaped and has over its concave surface an annular metal liner which is the front of casing 43. As is well known, the effect of the V shaped cavity is to concentrate the force of the explosion and localize its effect. When the V shaped cavity is lined or covered with a layer of metal the explosion acts to transmit jets of molten metal together with jets of gas from the explosion of the charge so that the object to be cut is subjected to jets of both metal and gas. The explosive used may be TNT, Amatol, RDX and similar explosive. The metal used for the metal casing 43 over the explosive charge 42 is preferably lead as it can be readily formed into an annulus.

The cutting charge of V shaped annulus of explosive covered with the metal sheath or casing 43 is made by filling a lead cylinder with explosive, sealing it at both ends and rolling the filled cylinder on a V shaped die progressively until the desired shape is attained and until the otherwise deleterious. Lower and upper exposive cutters .4 required amount of explosive per length is obtained. This is conventional practice.

' The buffer element ll plays an importantpart in this invention as it insures reliability in the operation of the device and aids materially in controlling the detonation of the explosive cutting charge 42. It servesto buffer the force of the explosion of the explosive cutting charge and prevent shuttering of the back-up annulus.

Seated in wells 44 of the groove 40, 180". apart are the detonation trains 45 comprised of detonator 46 of lower order explosive and lead in explosive charge 48 of a higher order explosive. The explosive of the detonator may be lead azide or similar explosive and that of the lead in charge '48'may' be PETN, RDX, or other type higher order explosive. The purpose of the detonation train is, of course, to build up a detonation wave to detonate the explosive cutting charge. The lead in explosive charge 48 may be dispensed with if desired and the det onator 4-6 used alone. The explosive charge 48 is seated in metal sleeve 52.

Lead wires 54 are potted in the'annulus 32 with plastic 55 as shown to conduct an electrical charge to the detonator 46.

Referring now to FIGS. 5, 6 and 7'there isshown one I modification of the lower cutter 14 comprised of heavy steel annulus 56 and crossbars 58 and 6t) supporting a switch mechanism 61, conduit 62 and plug'63. The con duit 62 carries the electrical wires for the switch and as ,sociated circuit to be described later. Crossbar 58 in this .means can be used for supporting the switch and conduit 62. The main purpose of the crossbars 58 and etl is to stop the cut out portion as it moves outwardly after explosion of the explosive cutter'so 'it can be retracted by the.

spring 24. I

In FIG. '6 the construction of the annulus 56 of the lower cutter 14 and its'assoeiatedelements: is seen to bev similar to that of annulus 32 of the upper cutter 16. Like numerals with primes are used to indicate like parts. The annulus 56 has an annular groove 40 in its lower edge passing completely around the annulus. Like the annular groove 40 of the upper cutter 16, it is V shaped in cross section and it is an important feature of the invention that these grooves are V shaped or in the shape of an arch rather than rectangular in shape. As stated above, the arch shaped cross section of the groove in contrast to a rectangular cross section makes the backup annulus much stronger and helps to prevent shattering thereof because there are no square corners to constitute points of weakness around the groove. The annular bulfer element 41 of plastic or other non-metallic material is seated in the bottom of the groove 40 and the V shaped explosive cutting charge 42' with the metal liner 43' covering its concave facing surface is seated on the plastic buffer element 41. The plastic element 41' is seated in the groove 40' by molding. The annular explosive cutting charge 42' may be made as explained above by first constructing an annular lead sheath of the proper V shaped construction and packing the explosive in the sheath. It can also be constructed by molding the annular explosive charge into the required shape and then encasing it in the lead liner.

Wells 44 are provided in the annulus degrees apart and they contain the explosive train comprising det-' onator 46' and the lead in explosive charge 48 surrounded by metal sleeve 52'.

A switch 64 and associated circuitry is supported at the intersection of the crossbars 58 and 60. As shown in FIG. 10, the operation of the circuit to provide sequential explosion of the explosive cutters is as follows: The circuit is shown in the safe condition with outwardly biased button 66 (FIG. 6) in the inward position. So long as the current flows through the switch of the liquid outlet cutter the lock-out relay will be deactivated to cut olf the firing circuit to the air inlet cutter. When the event control switch is closed to admit current to the detonators of the outlet cutter and actuate the explosive cutter, switch 64 will be actuated by the outward movement of the cut out portion 28 to release switch element 66 cutting oif current to the relay and thus permitting current to reach the detonators of the air inlet cutter. When the lower cutter 14- is mounted on the tank wall as shown in FIG. 1 the actuating pin 66 is depressed into its retracted or first position by tank wall portion 68 enclosed by the annulus 56. This construction and operation insures sequential actuation of detonators 46 and 46 with the resultant sequential cutting of the lower liquid outlet hole in the bottom of the tank and upper air inlet hole in the top of the tank in that order.

The operation of the explosive cutting mechanism utilizing the lower cutter modification of FIGS. 5 and 6 will now be described. The lower and upper cutters 14 and 16, respectively, are mounted on tank 10 as shown in FIG. 1 in the proper position. The tank filled with corrosive or other type liquid is mounted underneath the wing of an airplane by means of mounting lugs 12. With the lower cutter 14 mounted on the tank wall the actuating pin 66 will be depressed inwardly by contact with tank portion 28 to be cut out and thus held in a position representing the safe condition of the circuit. Upon actuation of the event control switch the detonation trains comprised of detonators 46' and lead in explosives 48 will be actuated to detonate annular V shaped explosive charges 42' to cut out portion 28 from the tank and form the liquid outlet hole. Upon the movement of cut out portion 28 outwardly the actuating pin 66 will be released to its outward position thus permitting current to flow to the detonators of the air inlet cutter 16 as explained above with the result that the cutter is actuated to cut the air inlet hole. It is thus seen that the construction and operation of the device provides for sequential cutting of first the bottom liquid outlet hole and second the upper air inlet hole. As explained above, this cutting sequence is necessary so that all of the liquid leaving the tank will pass through the liquid outlet hole and none will escape through the air inlet hole to cause damage to adjacent parts of the airplane wing or to personnel in the aircraft.

The sequential actuation of detonators 46 of the upper cutter i6 is of course effected by the movement of cut out portion 28. In this illustrative modification, the movement of the cut out portion 28 is outwardly thus permitting actuation pin 66 to move to its outwardly biased position. However, if desired the construction of the switch and actuating pin can be such that the pin moves inwardly to a second position.

A preferred modification of the lower explosive cutter for the fluid outlet opening is shown in FIGURES 8, 9 and 11. FIG. 8 shows the preferred method of mounting the cutter on a door covering the fluid outlet hole so that the hole is cut in the door. The tank can be reused merely by supplying a new door after use. This same method of using a door to cover the outlet hole and cutting a hole in the door is the preferred way of using the previously described modification.

A door 68 and circular adapter 21 are mounted over the lower fluid outlet hole by means of studs 72 and nuts 74. The adapter is of circular configuration and is provided with threads on its upper internal surface. The explosive cutter 14 is inserted inside the adapted and secured therein by means of circular securing ring 76. In this construction of the lower explosive cutter 14 the switch may be located in the annulus 56 or at any other convenient location. The actuating pin or button 66 for the switch protrudes inside the annulus 56 as shown. The actuating pin 66 is spring biased into the outward position representing safe position of the circuit of FIG. 10. When the button 66' is pressed inwardly by the cut out portion 28 moving outwardly the detonators 46 of the air inlet cutter are activated as explained above.

Referring to FIG. 9 it will be seen that the groove 40' in the annulus 56 does not extend all the way around the annulus. In this modification the detonators 46' are located at the end of the grooves so that the explosive cutting charge 42 in the groove is end initiated. This construction with the explosive cutting charge not extending through 360 results in the cutting of an are which does not extend through 360 so that the cut out portion 28 takes the form of a lid with a hinge on it when the explosive cutting charge is actuated.

In the operation of this modification, when the event control switch is closed to activate the explosive cutting charge of cutter 14 cut out portion 28 is formed leaving a hinge portion attaching it to door 68. The path and final position of the edge of cut out portion 28 is indicated by dotted lines in FIG. 8. As the cut out portion 28 moves outwardly after the explosion it presses button 66' into its inward position thus activating detonators 46 of the upper explosive cutter for the air inlet hole.

This construction provides for sequential actuation of the lower explosive cutter for the fluid outlet hole and the upper explosive cutter for the air inlet hole, respectively. It will be seen that in this modification as in the first modification the firing circuit which actuates the detonation train for the upper explosive cutter for the air inlet hole can only be activated by movement of the cut out portion 28 for the liquid outlet hole after it has been out out of door 68. In other words, in both modifications it is impossible for an upper hole to be cut until a lower hole has been cut. The movement of the cut out portion 28 for the liquid outlet hole actuates the circuit for detonation of the explosive charge for the upper air inlet hole in both modifications.

Experimentation has proved that the cut out portion for the holes moves outwardly rather than inwardly after the explosion and explanation for this is as follows. When the explosive of the cutter is detonated a pressure is created at the face of the liquid which force the cut out portion outwardly since the liquid is incompressible. The same effect is not achieved with the small cutter as by the time it is sequentially initiated some liquid has left the container and the cut out portion will move in- Wardly.

In FIG. 11 there is shown a modified form of actuating means for activating the detonating circuit for the upper air inlet cutter by outward movement of cut out plate 23. In this modification a connector is included in the circuit and the detonators of the upper air inlet cutters are activated by severing of the connector 80 by outward movement of the cut out plate 28. The connector may be in the form of a continuous wire with a weak portion at the breaking point, or a plug 82 and mating prongs 84 may be included in the connector for breaking the circuit by outward movement of cut out plate 28.

It is important that the connector 80 be properly connected or anchored at its ends in the annulus 56 of the cutter, otherwise loose fragments may be formed by breaking at the edge of the annulus or otherwise, with resultant serious damage to the aircraft or personnel therein. To avoid this the ends of the connector are anchored as shown inside the annulus on opposite sides so that the connector will not be severed by the edges of the annulus. Channels 86 and 88 are formed on opposite sides of the annulus 56 extending from groove 40 to the upper edge of the annulus. The connector is anchored in channel 86 by one end as at 90 and in channel 88 at the other end by means of anchoring ball 92. The connector is, of course, anchored in the annulus before buffer material 41' and the explosive cutting charge 42" are seated in the groove 40.

The invention has been described by its application to a container mounted on an airplane; however, it is not limited to this application as it can be used in any application Where sequential cutting is required. The invention includes the explosive cutter per se and is not limited to its use in the sequential cutting application. The invention has been illustrated with the use of two detonators but is not limited to such use as one or more detonators may be used, two detonators being preferred for purposes of redundancy. The invention is not restricted to the use of the non-metallic buffer element 41, 41' but the use of this element is preferred and it is an inventive feature of the explosive cutter per se. In the claims when the cutters are referred to as being located on the container or tank this language includes location of the cutters either on the door 68 or on the tank 10 itself. The firing circuit shown in FIG. 10 is, of course, conventional and optional as other conventional firing circuits may be used.

It is therefore to be understood that various modifications and changes may be made in the construction and arrangement of parts of the present invention without departing from the spirit and scope thereof as defined by the appended claims. Various changes and modifications may be made in carrying out the present invention without departing from the spirit and scope thereof. Insofar as these changes and modifications are within the purview of the annexed claims, they are to be considered a part of this invention.

What is claimed is:

1. Apparatus for the sequential cutting of holes in a container comprising: a first explosive cutter to be located at a first position on said container for cutting out a first portion thereof; a second explosive cutter to be located at a second position on said container for cutting out a second portion thereof; and actuating means operative upon movement of said first portion after it has been cut out to activate said second explosive cutter to cut out said second portion.

2. Apparatus of claim 1 in which each of said explosive cutters comprises: a heavy metal annulus having an annular groove in its bottom edge facing outwardly; an annular concave explosive charge positioned in said groove with its concave surface facing outwardly; a concave metal lining on said concave surface conforming thereto; and at least one detonation train for detonating said explosive charge.

3. The apparatus of claim 2 in which an annular backup layer of non-metallic material is positioned between the bottom of said annular groove and said explosive charge.

4. The apparatus of claim 2 in which said actuating means is a connector extending across said annulus and having both of its ends anchored internally of said annulus.

5. Apparatus for dispensing liquids comprising: in combination, a container to be supported above the ground; a first explosive cutter located on the bottom of said container for cutting out a first portion thereof; a second explosive cutter located on the top of said container for cutting out a second portion thereof; each of said explosive cutters comprising a heavy metal annulus having an annular groove in its edge facing said container; an annular concave explosive charge positioned in said groove with its concave surface facing outwardly; a concave metal lining on said concave surface conforming thereto; an annular backup layer of plastic material positioned between the bottom of said annular groove and said explosive charge; at least one detonation train in each of said explosive cutters for, respectively, detonating said explosive charges; and actuating means located adjacent said first explosive cutter operable by the movement of said first portion after it has been cut out to activate the detonation train of said second explosive cutter.

6. Apparatus for the sequential opening of holes in a container, comprising: a first door mounted at a first position on said container; a first explosive cutter located on the outside of said first door for cutting out a first portion thereof; a second door located at a second position on said container; a second explosive cutter located on the outside of said second door for cutting out a second portion thereof; and actuating means operative upon movement of said first portion after it has been cut out to activate said second explosive cutter to cut out said second portion.

7. The apparatus of claim 6 including a circular adapter mounted over each of said portion with said explosive cutters being mounted in respective adapters.

8. The apparatus of claim 7 including a circular securing ring for each adapter for securing the explosive cutters in their respective adapters.

9. The apparatus of claim 1 in which said actuating means includes an actuating member held into a first position by said first portion before it is cut out and spring biased toward a second position in which said second explosive cutter is actuated.

10. The apparatus of claim 1 in which said actuating means is normally in a first position and is operable by movement of said first portion after it has been cut out to be moved to a second position for actuating said second explosive cutter.

11. Apparatus for dispensing liquids comprising: in combination, a container for holding liquids having a lower liquid outlet hole; a door over said hole; a first explosive cutter having an annulus mounted on said door for cutting out a first portion of said door; a second explosive cutter located at a second position on said container for cutting out a second portion thereof; actuating means for actuating said second explosive cutter; and an actuating element in the path of travel of said first portion after it has been cut out and operative thereby to actuate said actuating means.

12. The apparatus of claim 1 in which said actuating means is a connector extending across said first explosive cutter and having both of its ends anchored internally of said cutter.

13. Apparatus for the sequential cutting of openings in an element, comprising: a first explosive cutter to be located at a first position on said element for cutting out a first portion thereof; a second explosive cutter to be located at a second position on said element for cutting out a second portion thereof; and actuating means operative upon movement of said first portion after it has been cut out to activate said second explosive cutter to cut out said second portion.

References Cited M. CARY NELSON, Primary Examiner.

W. R. CLINE, Assistant Examiner. 

1. APPARATUS FOR THE SEQUENTIAL CUTTING OF HOLES IN A CONTAINER COMPRISING: A FIRST EXPLOSIVE CUTTER TO BE LOCATED AT A FIRST POSITION ON SAID CONTAINER FOR CUTTING OUT A FIRST PORTION THEREOF; A SECOND EXPLOSIVE CUTTER TO BE LOCATED AT A SECOND POSITION ON SAID CONTAINER FOR CUTTING OUT A SECOND PORTION THEREOF; AND ACTUATING MEANS OPERATIVE UPON MOVEMENT OF SAID FIRST PORTION AFTER IT HAS BEEN CUT OUT TO ACTIVATE SAID SECOND EXPLOSIVE CUTTER TO CUT OUT SAID SECOND PORTION. 